March 11, 2011
The cooling system failed at three reactors of the quake-hit Fukushima No 2 [Daini] nuclear power plant Saturday, the operator Tokyo Electric Power Co said. The company, which has already scrambled to deal with radiation leaks at its Fukushima [Daiichi] No 1 plant, notified the industry ministry that the failsafe system at the No 2 plant stopped functioning as the temperature of coolant water has topped 100C.
3 nuclear reactors in trouble after Japan quake
March 11, 2011
TOKYO — Coolant systems failed at three quake-stricken Japanese nuclear reactors Saturday, sending radiation seeping outside one and temperatures rising out of control at two others. Radiation surged to around 1,000 times the normal level in the control room of the No. 1 reactor of the Fukushima Daichi plant, Japan’s Nuclear and Industrial Safety Agency said. Radiation — it was not clear how much — had also seeped outside, prompting widening of an evacuation area to a six-mile radius from a two-mile radius around the plant. Earlier, 3,000 people had been urged to leave their homes. Tokyo Electric Power Co. said Saturday that the temperatures of its No.1 and No.2 reactors at its Fukushima Daini nuclear power station were rising, and it had lost control over pressure in the reactors.
Fukushima Daini station is the second nuclear power plant the company has in Fukushima prefecture in northeastern Japan, where the troubled Fukushima Daiichi plant is located. Tepco said at about 2:46 p.m. local time three of its six reactors shut following the earthquake. All are boiling water reactors. Tepco said the reactors shut due to the loss of offsite power due to the malfunction of one of two off-site power systems. That triggered emergency diesel generators to startup and provide backup power for plant systems. About an hour after the plant shut down, however, the emergency diesel generators stopped, leaving the units with no power for important cooling functions.
Nuclear plants need power to operate motors, valves and instruments that control the systems that provide cooling water to the radioactive core. Earlier, Chief Cabinet Secretary Yukio Edano said, “Residents are safe after those within a 3-kilometer (1.8-mile) radius were evacuated and those within a 10-kilometer (6.2-mile) radius are staying indoors, so we want people to be calm.” The country’s nuclear safety agency said pressure inside one of six boiling water reactors at the Fukushima Daiichi plant near Onahama, some 170 miles northeast of Tokyo, had risen to 1.5 times the level considered normal.
Japan warns of small radiation leak at nuclear plant
March 11, 2011
Japanese authorities have warned there could be a small radiation leak from a nuclear reactor whose cooling system was knocked out by the earthquake. Technicians at the Fukushima Daiichi plant are set to release vapour from the unit in question to lower the pressure and prevent a meltdown. This carries a risk that a “small” amount of radioactive material could leak, officials say. Around 3,000 people have been evacuated from the surrounding area. These are residents who were within a 3km (1.86 miles) radius of the plant.
But early on Saturday morning, local time, people living within 10km (6.2 miles) of the plant were asked to leave. Eleven reactors at four nuclear power stations automatically shut down when the earthquake hit on Friday, but officials say this one reactor’s cooling system failed to operate correctly. The prime minister declared a “nuclear emergency” – under Japanese law, an emergency must be declared if a cooling system fails, if there is a release of radiation, or if there is a dangerous level of water in the reactor. Japan’s nuclear safety agency said pressure inside one of six reactors at the plant, some 270km (170 miles) north east of Tokyo, was considerably higher than normal.